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Solved Z axis now too fast and too far

Discussion in 'Troubleshooting' started by DGGT6, Nov 4, 2019.

  1. DGGT6

    DGGT6 New Member

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    A funny thing happened after replacing my ramps 1.4 board...................
    The Z axis now seems to travel 4 time as far as requested, Move 1.0mm gives about 4mm and Move 10mm gives about 40mm. The speed is also VERY much faster (four times???)

    I thought I had just done a straight swap of the connectors from one board to the other????? If I had plugged something in incorrectly, would it cause this problem?

    I tried re-sending to the arduino with no change, then I tried changing the Z steps from 400 to 1600 (factor of 4??) also with no change.

    Any thoughts on what I have done!?

    I did the ramps change as I was getting thermal runaway on the hot end. I thought I had traced it to the mosfet and resoldered a new one in. Curiously there was no observable damage/burn to the mosfet. This also did not solve the runaway problem, so I replaced the whole (white original ROBO??) board. This did solve the runaway problem.
    Is it unusual the the hotend mosfet "fails"?

    Thanks for any assistance,
    Cheers,
    Doug
     
  2. DGGT6

    DGGT6 New Member

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    Well this is getting weirder......
    Couldn't find anything the same on the internet so tried changing my Z steps to 100 (instead of 400) and the Z travel is now accurate 1mm = 1mm. The travel speed has also decreased to somewhat normal but it sounds "strained" when homing the last few mm.
    Curiouser and curiouser......
     
  3. DGGT6

    DGGT6 New Member

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    The problem turned out to be the little jumpers under the stepper sticks.
    I replaced all 6 for the 2 Z axis sticks and BINGO.
    Thanks to "DUST" over on the REPRAP forum for a quite and accurate diagnosis!!

    Cheers,
    Doug
     
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  4. Geof

    Geof Volunteer Moderator
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    They are so easy to overlook. I did a thread on ramps replacements, the most missed step is those jumpers :)
     
  5. DGGT6

    DGGT6 New Member

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    Hi Geof,
    with my fat fingers I needed my mini needle nose pliers to get the little buggers out. I did crack/slightly damage a few of the "thousand" jumpers but they appeared to be "serviceable". Obviously NOT!:mad:
    I guess it is lucky that I am a rocket scientist and not a brain surgeon;)

    Cheers,
    Doug
     
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  6. Geof

    Geof Volunteer Moderator
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    The important thing is you got it :) we won’t talk about how many I’ve missed or destroyed over the years :)
     

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